Wettable and dispersible thiocarbanilide



Patented Aug. 21, 1945 I UNITED STATES PATENT orrics v sesame Robert Ben moi, sol-mane, com, assignedto American Cyanamld' Comm, 1 N. Y., a corporation of Maine No Drawlng.s

Application August m, 1944. erial No. 548,931

12 Claims. (Cl. 252-41) I r r the weight a the thlocarbanilide. The eifective This invention relatesto an improved dispersible thiocarbanilide.

Thiocarbanilide is an extraordinary effective froth flotation promoter, particularly for sulfide and precious metal ores. In the past, however. its

use has been greatly restricted because it is very insoluble in water and is not easily wetted.

A thiocarbanilide reagent has been prepared by dissolving thiocarbanilide in dithiophosphates such as dicresyl dithiophosphoric acid, dialkyl dithiophosphoric acid and the like. Certain of 1 these reagents have been used extensively inthe froth flotation f sulfide ores. But they are sub- 'iect to the limitation that only a small amount of thiocarbanilide can be dissolved. ranging from 6 to not more than Thus, the reagent is a dithio phosphate reagent and the thiocarbanilide constitutes only a minor, although im- P rtant part.

D. W. Jayne (U. 8. Patent No. 2,185,591) developed a new form of thiocarbanilide the individual particles 01' which were coated with a film of hydrophilic protective agent such as carbohydrate gums. lignin sulfonates, saponins, and the like.' Preferably the particles were also coated with a powerful wetting agent such as a sulfonated alkylnaphthalene, sulfated alcohols, esters of sulfosuccinic acid, and the like. Jayne found that thethiocarbanilidetreatedaccordingtohisinvention was eflective as a sulfide reagent even though it was not soluble in the flotation pulp but was present only in a line and uniform dispersion. The dispersible thiocarbanilide of Jayne was an immediate success. However, on extended use it was found that in the froth flotation of certain ores diiliculties were encountered and it was not universallyapplicable. I h V According to the present invention. 1 have found that if 'thiocarbanilide is coated with a small amount of a sulfid promoter such as a dithiophosphate, a xanthate, a water soluble mercaptobenzothiazole and the like, the particles of thiocarbanilide disperse with the same as though treated with protective colloids and wetting agents as described in the-Jayne patent. At the same time no difllculty is noted fromexcessive foaming in the flotation cell and improved metallurgical result are obtained.

'lli'he present invention should not be confused with reagents which were prepared by dissolving a. minor portion of thiocarbanilide in a major portion of dithiophosphoric acid. In the present invention the sulflde promoter such as a dithiophosphate is present as only a minor constituent normallyamountingtoonlysmallpercentageoflt Promoter is the thiocarbanilide and the small amount of the other sulfide promoter, while probably eifecting collection in a minor way, primarily tends to alter the physical characteristics of the thiocarbanilide so that it disperses readily and is thoroughly wetted.

It is important that the small amount of the of a dispersing or, deflocculating agent may be used to improve the uniformity of mixture and maybeinoorporated eitherintothepasteordry products. These deflocculating agents include some of the products as described in the Jayne patent and also include other common dispersing or deflocoulating agents such as disultodinaphthylmethane. The purpose of or deflocculating agents in the present invention is to improve the mixture of the small amount of sulfldereagentswiththethiocarbanilideandtoimprovet,theilityoftheflnished product. The fact that improved metallurgical resultsareobtainablewiththeproductsofthe present invention which do not contain protective colloids shows that the minor amounts of protective colloids which are present in some products do not exert any material efiect in flotation.

The pastes which are obtained when the sulflde p q oter and the thiocarbanilide are mixed are dispersed readily in water, and are preferred in certain flotation operations. However, many sulfldeoresarelocatedinremotepartsofthe world and present a serious transportation problem when pastes are used. It is, therefore, an importantpractical advantage of the present invention that the coated thiocarbanilide may be obtained in the form of dry powder which keeps well. and presents no problems of transportation.

1 These dry powders, if properly prepared, show the -sameraiiidanduniformdispersionpossessedby drier, so as to prevent coagulation of any colloidal protective agents which may be present. The preparation and use of dry powders prepared as above by dry milling and mixing obviates the necessity of drying and gives uniform dispersions.

The froth flotation of sulflde ores is a very old art and has been brought to a high state of emciency. Many ores treated are extremely low grade and the cost factor is oi primary imporflotation density, floated for 3 minutes in 9. FBI;-

ergren flotation machine. The ore was then conditioned for 3 minutes with an additional 0.1 lb./ ton of the thiocarbanilide and floated for 3 minutes. 0.26 lb./ton of the pine oil was used as a frother. The results of these flotation tests are summarized in the following table.

First Second 31o.

oen 11 roent u Thiocarbanilide used Egg,

Distribu- Distrihution my tion Thiocarbanilide 14. 76 I 21. 34 14. 76 16. 21 37. 65 Thiocarbanilide 17 sodium isopropyl naphthalene sullonate i4. 06 iii. 63 i7. 70 l9. 2] 34. 83 Thiocarbauilide l potassium amyl xanthste i8. 11 i8. 53 19. 02 50. 22 68. 75 Thiocarbsni lide ammonium (ii-sec. butyl dithiophosphate 254B 40. 32 16. 58 50. 65 90. 97 Thioesrbsmlide 8.7% sodium salts oi mercaptobenzothiamle 10. 22 2%. 68 14. 90 M. 46 78. 14

described in the Jayne patent was used, is not v resent. This represents an important operating advantage. I

The invention will be described in reat r d tail in connection with the following specific examples. The parts are by weight.

Example 1 Example 2 A series of thiocarbanilides was prepared as described in Example 1, except that in addition to the sulfide reagents, a deflocculating dispersing agent was included in the mixture in order to make the working easier and improve the uniformity of the product.

The procedure of Example 1, was used including the same amount of reagents.

' 40 The metallurgical results are summarized in A series oi thiocarbaniiide sulflde reagents were the following table.

First (i060. secondtegnc. percen u peroen u Thiocarbonilideused gz i Distrihu- Distribu- Amy tion my tlon Thiocarbanilida 14. 70 21. a4 14. 1c 10. 21 a1. Thiocarbanil'd 1 sodiumiso r0 lnaplithslene sulionste soap bark 15.70 18.28 10.05 21.53 38.81 Thiocsrbaniiidg 5% tassium mg'fxanthaw 1% disulfodinl z thyl-melam o 8. 35 35. 26 12. 67 52. 51 87. 77 Thiomrbanilide 1 sodium disec. butyl dithiophosphate oi an evaporated residue from the fermentation oi molasses to produce alcohol-sold in the trade under the name FMR 22.68 37.63 16.38 1.18 Thiocarbanilit e 4% oi 1:1 mixture oi sodium diethyl and disco. butyl dlthio phosphates;

1% crudecaciumligninsuliona 21-10 3244' 16.55 51.46 83.80

iocsrbanilic e2.67 oi 1:1 mixture oi sodium diethyl and disco. butyl dlthio phosphates.-

1 a crude osmium ignin sulionate 2 .8 28. 91 16. 32 50.15 79.00 Th ocarhanilide 6% ammonium dicresyl dlthio phosphate; 1.6% sodium hgninsulionste. so. 91 29. .17. 96 68. 93 83. 69 Tbiocsrbaniiide 8.7% sodium salt of mermptobenzothiazole 5% crude calcium llgmn suilo tn 10.2! 15. 21 17.44 66.34 71.65

prepared. The first was untreated; the second had incorporated 1% sodium isopropylnaphthalene sulionate. Three other thiocarbanilides were prepared by working a paste, containing from 10 to 30% water and consisting of thiocarbanilide and 10% potassium amyl xanthate, 5% ammo I nium di-sec. butyl-dlthio phosphate and 8.7%

sodium salt of mercaptobenzothiazole respectively. The pastes were mixed thoroughly until a uniform paste was obtained. These products dispersed in water and were fed to flotation as suspensions in water.

A copper. ore from the Western United States assaying about 4% copper, and containing chalcopyrite, chalcocite, covelite, enarglte, pyrite, and

various silicate minerals, was ground with 0.15 lb./

aiter dilution to ton of the thiocarbanilide and,

It will be apparent that the best results are obtained by using the dispersible thiocarba'nilides oi the present invention. Best recoveries with high grades are obtained with the dithiophosphate modified thiocarbanilides. The poor result obtained in the second test, which is with one of the commercial reagents prepared according to the Jayne patent was due possibly to the tion with the Jayne It is-an advantage of the present invention that it canbe used effectively with ores where the former disv persible thiocarbanilidos were not practical Example 3' Tests were undertaken to determine what im- -provements were obtainable-when thiocarbanilide is added to the flotation cell instead of tothe grindasinExamples1and2. The ore used was the same as in Examples 1 and 2 but was ground, diluted to flotation density, and then conditioned for 2 minutes with 0.15 lb./ton oi thiocarbanilide followed by flotation-in Pagergren flotation machine. The pulp was then conditioned with an additional 0.15 lbJton of 121110- carbanilide and again floated Ior'3 minutes; in

all operations 0.026 lb./ton of pine oil was used. In the first test thedispersible thiocarbanilide of the second test of Example 2 was used, that is to say, the one workedwith the isopropyl naphthalene sulfonate and soap bark. In the second test the thiocarbanilide was prepared by dry mixing the thiocarbanilide with 4% of 1:1 mixture of sodium diethyl and di-sec butyl'dithiophosphates and 1% crude calcium lignin sultonate.

The metallurgical results are summarized in the following table.

First concentrate Second concentrate percent Cu percent Cu Total Cu Test No. Distribu- Distribum tion tion v I 1 21.0; nos 15.134 42.13 can 2 23.40 2e 50 a co 1s 57 as. 01

It will be apparent that with this procedure, a great increase in recovery and a material improvement in grade was obtained. It will be noted that the recovery was higher in the first concentrate oi. the second test than in both concentrates combined in the first test, that is,

76.5% as compared to about 62.8%. This accounts for low middling product in Example 4 Tests were run on a Missouri lead ore with the reagents of Example 3. The first test thiocarbanilide containing the isopropyl naphthalene sulfcnate and soap bar while the second test 2.

' used that containing the dithiophosphates and lignin sulfonate. The ore contained galena, pyrite, chalcopyrite, mareasite, limestone, and quartz and assayed about 4% Pb. The ore was ground with 0.10 lb./ton thiocarbanilide added 7 in dry form, 1.50 lb. lton trisodium phosphate and 0.25 lb./ton sodium cyanide, diluted to flotation patent is eminently suited there is still an imstoic mam mixture oi sodi- 2.51pm ammonium di-isopropyl provement when a dispersible thiocarbanilide oi the present invention is used. Both recovery and grade show increases.

When the dispersible thiocarbanilides oi the present invention described in the preceding examples are prepared in paste form or by drying under vacuum or by mixing the ingredients, the products obtained show the same metallurgical results within thelimits 01. error of ordinary flotation tests.

The following table gives the composition of a series or dispersible thiocarbanilides which can be prepared according'to the present invention.

In every case a product is obtainedwhich dis-' perses readily and which shows the improvements described in the foregoing examples.

100 parts thiocarbanilide with:

As wetting agent Deflocculatiug agent 0.5 to 2 parts crude calcium ligninsulionate.

1Ito-2 parts sodium lignin sulona l to 2 parts calcium lignin sulona 2 parts calcium lignin sulionate.

1-2 parts 'lauak L (condensation product oi formaldehyde and naphthalene suiionic acid).

1 part calcium lignin sulionate 1 to iii-parts cal umligninsulionate crude). ct

1 art calcium lignin sulionata crude).

um ethyl and di-secondary bulgyl dlthio phosphates.

5 to 10 arts sodium di-ethyl dithiop osphate.

2 to 10 1:1 mixture of sodium iethyl' and di-socondary butyl dithio phosphates.

2.5 to 5 parts sodi um secondary butyl xanthate. 2 to 6 parts sodium di-isopropyl dithiophosphate thiophosphate. ammonium hiophosphate. Mipartsammoniumdl-secondary butyl ditlgigghosphatc. 2.5 um di-isopropyl dit io phosphate.

di-ethyl disuiionate (crude). 1 art calcium llgnin sulionate crude).

. a which a dispersible thiocarbanilide oi the Jayne l'part'lanakLcaieiumllgnin gaparts 1:1 mlxtureoi sodium Do IFS 0f mercaptobenzothiazole 40 anddi-sooondary butyl dithiophosphoric acid.

5 was sodium salt of mercaptonzothiazols. 2.5 to 6 parts sodium secondary butyl xantbato 2.5 parts sodium ethyl xanthatm- 2.6 parts potassium 'lsopropyl 2 amyl ran thato 2.5 arts 1:1 mixture oi sodium thyl and di-secondary butyl lpart Tauak L.

Do. Do.

1 calcium lignin sulfonate crude).

1 part Tanak A (condensation product of formaldehyde and dithiophosphate. naphthalene suli'omc acid Do 1 part Sa r Brown. Do lpartE R 2 to ilinpans sodium di-isopropyl 1 part uigrosme (water'soluble).

dit ophosphate.

Do 1 part yellow corn dcxtrine.

1 part sodium sulionate. Dom, 1 part calcium lignin sulfonate. 2.5 parts sodium di-secondary 1 part Blanool- (condensation 55 butyidithiophosphate. product oi formaldehyde and density, and floated 1dr 5 minutes. The results 7' ing concentrate was cleaned by refioating for 2 minutes; 0.03 Ib./ton of a. higher alcohol Irother, sold in the trade under the designation, 3-23, was added to each oi! the flotation operations as a frother. The metallurgical results the following table.

Cleaner concentrate, Percent Pb Assay Distribution This example shows that even with ore for appear in naphthalene sulionic acid).

thiocarbanilide the individual particles 01 which motor being present in a minor proportion in are coated with a film of a sulfide promoter selected in the group consisting of organic esters .of dithiophosphoric acid, xanthates and water soluble mercaptobenzcthia'zoles, the sulfide procomparison to the thiocarbanilide and the coating being sufilciently uniform to produce a product which is readily dispersible in water and in the pulp in iroth flotation operations.

2. A free flowing dispersible thiocarbanilide promoter in which the individual particles of which are coated with afilm oi sulfide promoter selected in the group consisting of organic esters of dithiophosphoric acid, xanthates and water soluble mercaptobenzothiazoles, the sulfide promoter being present in a minor proportion in comparison to the thiocarbanilide and the coating being sufiiciently uniform to produce a product which is readily dispersible in water and in the pulp in i'roth flotation operations.

3. A dispersible thiocarbanilide according to claim 1 in which the sulfide promoter is a dithiophosphate.

4. A dispersible thiocarbanilide according to claim 2 in which the sulfide promoter is a dithiophosphate. I

5. A dispersible thiocarbanilide according to claim 1 in which the sulfide promoter is a xanthate.

6. A dispersible thiocarbanilide according to claim 2 in which the sulfide promoter is a xanthate.

7. A dispersible thiocarbanilide according to claim 1 in which the sulfide promoter is a water soluble mercaptobe'nzothiazole.

8. A dispersible thiocarbanilide according to claim 2 in which the sulfide promoter is a water soluble mercaptobenzothiazole.

9. A dispersible thiocarbanilide according to claim 1 in which the coating of the thiocarbanilide particles includes a minor portion of a deflocculating agent.

10. A dispersible thiocarbanilide according to claim 2 in which the coating of the thiocarbanilide particles includes a minor portion of a 'defiocculating agent.

11. A dispersible thiocarbanilide according to claim 1 in which the coating of the thiocarbanilide particles contains a mixture of dialkyldithiophosphates and at least one lignin sulfonate.

12. A dispersible thiocarbanilide according to claim 2 in which the coating of the thiocarbanilide particles contains a mixture of dialkyldithiophosphates and at least one lignin suli'onate.

ROBERT BEN BOOTH. 

